Chemical Science. 435 
posed by heat; with the alkalies it forms the peculiar salts, and 
when water is present, expels carbonic acid from carbonates of 
potash, ammonia, and barytes. When just covered with water, 
and iodine added to it, decomposition takes place, sulphuret 
of carbon, and a solution of hydriodic acid being produced. 
Iodine, added to the salt of potash, produces sulphuret of carbon 
and hydriodate of potash. 
Dr. Zeise then remarks on the probable existence of a pecu- 
liar compound of carbon and hydrogen, but mentions his inten- 
tion of extending his researches on this and some other subjects, 
and of giving his conclusions to the world at some future time. 
—Ann. Phil. N.S. iv. 241. 
2. On a peculiar Sulphate of Alumina, by Mr. Phillips.— 
Mr. Phillips obtained this salt by putting moist alumina into 
dilute sulphuric acid, and adding more occasionally, until it re~ 
mained in excess; being now filtered, a clear dense solution was 
obtained, which, when dropped into water, instantly let fall a 
precipitate as abundant almost as that from muriate of anti- 
mony. It also immediately began to precipitate even of itself, 
though no tendency of this kind was observed, as long as the ex» 
cess of alumina remained mixed with it. The deposition went 
on for several months; but the clear part was always preci- 
pitable by water. Another property of this sulphate of alumina 
is, that if heated to 160° or 170° Fahr., it becomes opaque and 
thick; but upon cooling, in a few days, becomes clear again, 
From an average of experiments, 100 grains of the solution 
(which, however, had been depositing for some weeks) when pre-~ 
cipitated by waiter in sufficient quantity, gave 5,23 gers. of sub- 
sulphate of alumina; 100 grs. of the solution on analysis gave 
5.27 sulphuric acid, and 5.38 alumina; 100 grs. of the spon- 
taneously~deposited salt gave 26,10 grs. of sulphuric acid and 
26.68 alumina. Hence the salt deposited and the salt in solu- 
tion appear to be the same: 
Sulphuric acid 40 the first, 40 the second, 
Alumina. . 40.83 AQO2 Yee 
Mr. Phillips considers the number 27 as representing the 
atom of alumina; the salt therefore will consist of 2 atoms sul- 
phuric acid 40 x 2==80, and 3 atoms of alumina 27 x3=81.— 
Ann. Phil. iv. 280. 
3. Effect of Cold on Magnetic Needles.—Dr. De Sanctis has 
lately published some experiments on the effect of cold in de» 
stroying the magnetic power of needles*, or at least of render- 
ing them insensible to the action of iron and other magnets, 
© Phil. Mag. \x. 199, 
2F2 
